21 November 2018 Analogue Printing Technologies

Big screen opportunities for print

Screen printing is perhaps the forgotten process, but as its role in display printing fades, now opportunities are continuing to open up.

Screen printing has frequently been considered the least subtle of printing processes. Ink, or perhaps a varnish, is forced through a mesh to reach the substrate beyond. It was associated with large display posters, the 48-sheet and bigger advertising hoardings that dot the motorways, city centres and railway land up and down the UK. That market has gone, lost to large format inkjet printing and where it remains, for the application of large areas of solid colours – red for a sale say, or a fluorescent which is hard to deliver with inkjet – nobody is investing in screen presses. Only they are.

These are not the great brutes of machines handling full out quad format sheets, but high precision presses able to print with fluids that are beyond litho or inkjet let alone flexo and gravure; able to print on substrates that are equally beyond the conventional processes and designed for work that is frequently outside the experience of the commercial printer.

The applications in industrial printing in short are booming and Sakurai is enjoying the results. Its rotary screen presses are designed for precise register, using the same sort of gripper and side lay systems that its offset presses employ to achieve the sub millimetre precision that was beyond the old Svecia machines where the print was to be viewed from 100 yards away, or at best, from across the railway tracks. Precise registration was not needed. But for producing touch panels, dashboard displays, part numbers and so on, precision is crucial. There is plenty of print in the average new car, well beyond the brochure and the owner’s manual, and Sakurai’s machines will be responsible for it.

The commercial printer is not ignored, though it is in finishing rather than ink on paper that Sakurai’s screen press excels. The screen technology can apply a deeper layer of high gloss or matt varnish than any other process. It can apply those metallic and fluorescent inks and now it can apply foils more effectively than other technologies.

The foil application, the Liquid Metal Embosser, was revealed in Europe at a recent open house where it was put through its paces with solid area and filigree enhancement across the full width of a sheet. It is an extra module that fits in the embellishment line, pressing the foil into a screen applied varnish. To this extent it is similar in approach to the foiling attachments to laminators, but without the limitations of paper or cost effective production run.

In this sense it slips between the ultra short runs tackled by the combination of digital press and laminator and the dedicated hot foiling press. There is no expensive die to produce, no heating up or cooling down between production runs, and a way of delivering high impact enhancement for short to medium runs for book jackets, folders, high end brochures and more. While the costs are not disclosed, the cost of ownership will be less than an MGI or Scodix, though there is the additional step of making a screen to create the mask for the foil.

At its Hounslow showroom, Sakurai has installed a Grunig system to demonstrate how painless this is. There is none of the heady smell that used to identify a screen print operation, nor any of the messy washing down area. Sakurai has the facility set up for training as well as demonstrations. “It is screen printing without the smell,” says country manager Claudio Moffa. “The LQM should appeal to an existing customer currently doing a spot varnish and to offset printers who want to take this work in house.

“It is also very clean for the sorts of printer with experience of digital printing. We know we have to make the process easier for these customers. To that extent it’s like a Scodix. We have the partners in place to supply the ink, varnish and the foil and the experience to help customers achieve the high build effects as well as the fine details which can be created in screen printing.”

And the screen process is more cost effective than the digital alternatives: inkjet ink and varnish is undoubtedly expensive. There are also limits to the amount of liquid that can be applied in one pass. To achieve high builds, inkjet must apply successive layers of fluid for example. A screen print varnish can cost €7 a kilo, the inkjet version can be ten times as much, with a significant impact on cost per sheet.

Moffa continues: “We will also provide an instructor, which is something that is normal in offset printing, but which is revolutionary in screen printing.”

For the industrial customers, this also means running training courses in Hounslow and acceptance tests. It means that when the press is delivered and installed, the user is ready to go into immediate production. This is because the customer has a defined application and demand to meet, rather than the traditional modus operandi of the commercial printer of making the installation and then trying to develop a market for it.

Stefan Keseler joined Sakurai in June as technical sales manager for the screen business. He began his career with four years studying print in Switzerland 25 years ago. “When I started I thought that screen printing was dying. The graphic display market had gone. But this is not so.

“Screen printers are smart people and they are adept at finding applications which will survive. Today screen printing is more about applying industrial layers where you can control the inks and the layers, printing with UV sensitive inks, thermally responsive inks and pressure sensitive inks. There are applications in electronics where printing conductive silver inks on films has replaced copper wiring. Screen printing is a very underrated form of printing.”

The printed electronic circuits end up in vehicles. There are touch panels while traditional dials used by automotive manufacturers are printed on screen presses because of the density of the inks that are possible on films. As printed instrumental panels are being replaced by programmable displays, screen printing has moved into production of the touch panels and sensors that cars now bristle with.

“In 25 years of working in screen printing I have not seen all the applications yet,” he says. “There are quite a few applications using the technology that I haven’t thought about. Screen printing is now part of a completely industrial process.

“This means that we are selling to process engineers who ask about the performance of the machine and what are the parameters that you can achieve. There can be three or four days of conversation about these parameters and about the specific process questions that they want to have answered: provide the right answers and you are in. We are not selling a machine, we are selling a solution.”

After production of the touch panels, applying the layers of conductive materials that will allow the software and the user to display whatever information is required, there will be a vast numbers of sensors to print as a step towards autonomous driving. Even the fuel cells that will power the car of the future can be part produced by screen printing he adds.

This diversification has been good for the company as sales to the commercial printing industry have stagnated. This sector of the market is very much a replacement business, though there are printers bringing more finishing in house and a growing demand for value add finishing with spot varnishes, high build varnishes and foiling. A deal like this was struck on the eve of the open house and the event attracted a number of printers as well as trade finishers. Carton printers are investigating the options particularly as luxury packaging concepts grow. “Everyone is looking for something special,” he adds.

And with something special there is a requirement for absolute consistency. This is delivered through the Maestro 102 NS, a screen press conceived as an inspection machine. Four high quality cameras sit above the sheet and check for flaws, for colour consistency and for marks that would render the box unsaleable. Inspection avoids very costly mistakes.

The scanning of the entire sheet will pick up flaws any bigger than 50 microns and takes place while the sheet is held in the front lays, consequently speed is restricted to 4,000 sheets an hour. It is a machine that was only introduced last year and to date ten have been sold in Japan where buyers are fanatical about quality. A version that uses the cameras to scan at lower quality while the sheet is moved on a conveyor is less expensive and faster. Any sheets that come up short are rejected so that those in the delivery have the ticket to prove they have achieved the right quality.

The big opportunity is in the industrial print markets and where opportunities extend to biotech as well as printed electronics. “There are applications which we have never imagined, that we never knew existed. This market is is fast moving, it’s changing and that’s what makes screen print so very interesting,” says Keseler.

The recent Sakurai open house event concentrated on applications for screen printing, half about enhancement for print, half for specific industrial applications. It also saw the reveal of the Liquid Metal Embosser.

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The screen process can deliver the finest quality print, say delicate foiling, as well as printing with high impact printing inks. Sakurai's Liquid Metal Embosser is an extra module that fits in the embellishment line, pressing the foil into a screen applied varnish.

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Stefan Keseler

Stefan Keseler joined Sakurai in June as technical sales manager for the screen business. “In 25 years of working in screen printing I have not seen all the applications yet. Screen printing is now part of a completely industrial process,” he says.